Fine crumb rubberlike polymerizates and methods for their production



Patented Mar. 2 1954 BERLIKE POLYMERI- FINE CRUMB RUB ZATES AND DUCTIONCharles Henry to Heresite & tion of Wisconsin N Drawing. ApplicationSerial No.

7 Claims. (01. 26083.3)

This invention relates to a fine-crumb polymerizate of butadiene andmaterial copolymerizable-therewith of a class consisting of styrene andacrylonitrile and to the method for producing the same.

This application is a continuation-in-part of my abandoned application519,200, filed January 19, 1944, and entitled Coagulation,Neutralization and Washing of Rubber-Like Polymerizates.

The ordinary methods for producing copolymerizates of styrene andbutadiene or acrylonitrile and butadiene result in a limited yieldrequiring the recovery of the individual reactants, which is anexpensive procedure, particularly in the case of butadiene. According tothis invention, it is possible to procure 95 to 100% coagulation into afine-crumb polymerizate. In the present process a soapy emulsion ofbutadiene and styrene or butadiene and acrylonitrile is produced bycombining these reactants with the necessary amount of soap to form theemulsion, and in addition thereto, adding 1% to 1.5% of a iii wettingagent. The invention may be used in the production of rubber of the typedescribed in the patent issued to me on April 14, 1949, as Patent No.2,463,382.

The purpose of this invention is to produce a dry polymer and toregulate the crumb size of the copolymerizate by the addition of awetting agent to the soapy emulsion of the raw materials. The purpose inachieving a fine-crumb size is to obtain a rubber product which iseasier to wash completely, neutralize, dry and mill. It is desirablethat the final crumbs have a diameter of .5 mm. to 3 mm. I do not seekto regulate the particle size of the copolymerizate but rather the crumbsize which is made up of a plurality of particles of the copolymerizate.

The mere addition of soap in excess of the amount necessary to form theoriginal soapy emulsion does not achieve the results of this invention.Addition of excess soap results in a crumb much coarser and larger thanthe crumb produced by my method. If the emulsion is produced through theuse of a wetting agent alone, without soap, addition of excess wettingagent will again produce a large lump, not a fine crumb.

The preferred wetting agents are of the sulfonic acid type. Either analkyl benzene sulfonate salt with from 10 to carbon atoms in the alkylgroup or an aliphatic naphthalene sulfonate salt with from 1 to 3 carbonatoms in the aliphatic group may be used as satisfactory wetting agents.The most satisfactory wetting agent was found to be sodium alkylnaphthalene METHODS FOR THEIR PRO- Hempel, Manitowoc, Wis., assignorChemical Company, a corpora- November 30, 1949, 130,368

Sodium isopropyl naphthalene sulfonate;

Sodium alkyl benzene sulfonate (mixed 10 to 20 carbons in alkyl group);

Decylbenzene sodium sulfonate;

Dodecylbenzene sodium sulfonate.

After the addition of the wetting agent and the complete polymerization,the latex is coagulated with a suitable coagulant such as 15-30% dilutehydrochloric acid or an alcohol.

An example of the process utilizes the following proportions ofingedients:

Parts by weight Butadiene Styrene 25 Potassium persulfate 3 10% soapsolution 112 Cyclohexane 5 Sodium hydroxide /3 to 5 The reactingingredients are processed in the following manner: a soap solution maybe made by adding 10% by weight of soap to warm water and agitatingvigorously until the soap has been r completely dissolved and thesolution cooled. To

this is added the styrene, free from inhibitor, and the mixture is againagitated vigorously for about 10 minutes. Then the sodium hydroxide,potas sium persulfate and cyclohexane are added together and agitatedfor about 15 minutes to form an emulsion. If desired be added at thistime. The emulsion is pumped into a pot equipped with an efficientagitator and built to withstand the required pressure. The butadiene isthen added and the mixture agitated and heated to 40 C. until thereaction pressure, which originally rises to 45 lbs. per square inch,drops to zero. At the completion of this time a white liquid is obtainedwhich may be designated a latex milk.

The proportion of styrene and butadiene may be varied, but normally theratio of butadiene to styrene is between the limits of 3:1 and 1:3.Derivatives of styrene may be employed to replace the styrene in wholeor part. Other the wetting agent may olefinic materials such asacrylonitrile may also reason produces a coagulate which is considerbeemployed. ably finer and more uniform in texture and size The resultingproductis substantially free from than was previously the case. Theordinary dimers. coagulate is in the form of large irregular lumps.

Themilky latexso obtained is treated with a 5These='lumps=entrap.considerableiquantities of small proportion;preferably from-;5'to of an Luncoagulated latex and: also makeitdiflicult t0 antioxidant, such as phenyl-B-naphthylamine. completeneutralization in washing.

If the wetting agent has not been previously The use of hydrochloricacid or alcohol simpliadded, it may now be included. The wetting fiesthe process of coagulation since it eliminates agent is added ineithermannermeremberore*wtheioperationwalled creami or y described in anamount which ranges from 110% "ployed"incopolymerization.

to 1.5%. The figure 1.00% is critical since it The use of the kneaderfor washing produces has bee f u d th t th e dditi rbfa a'-wetting abettenwashedrproduct because it retains the agent in any lesser amounts'produces.large lurnps c0agulatefimtheform of fine particles which areor one solid lump, The addition of a wetting 15 freelysuspendedgwhereasin former processes the agent in excess of 1.5% apparentlyhasnubeneparticle werersqueezed together on a mill. It ficial ordeleterious efiects on the desired fine 178150? aVOidS' transferring hal d n crumb size. Hence, for economy reasons, the Washing 0 betweenWashing a d y upper limit is 1.5%. If this process isfoll owd, t' sp wthe fi y divided crumbs crumbs having a diameter of from .5 mm. to 3 poduced by this P s to W sh Out a most al 11m areproduced; havingthe'ladvantag'es'lhere- -the' soap used'sin theroriginal=- emulsion.Hematoiiinb'efgrg s t o t fore artificial: rubber productsshavehadzilarge The' latex wh'ich= has 2been treated withw the ipercentages f i th s ap:- m i n th ebywr 3 addition of the'wettingiagent is then added to ew ari gqu l p ...an"equa,1 v 1ume 'of3dilutehydrochloric .acid The foregoing detailed descriptiOnhascbeBn 15-30" gl-0110 while-undergoing. violent given for clearness." of understanding;onlyrand agitation thereby jcausing'cgagulation 1 of :t :-no unnecessarylimitations:shouldbe-understood copolymerizateintothe:form; of smallwhitepa'rtitherefromcles having rubber-like qualities. claim:

Numerous experiments show that a fine crumb a'method iofi making?! MIubcan be produced 'only'with' certain. particular her-like p z tefromanaqueousemulwetting "agents. "Fonexample, the following i sion ofbuta'dieneanda material'flepolymerizable wetting agents were notsatisfactory: therewith of the class: oonsisting-otstyrene: and Smfatedoctadecanoic acid. acrylonitrilewherein theemulsion is=formedrbyoxygenated lauric acid mixing-with thebutadiene-andtheimaterialwwasodium lauryl Sulfate terandsoapinanamount.necessaryitotformithe sodium naphthalene ismfonate; emulsion,the stepwhrch comprises coagulating Sodiumisobiitlllnaphthalene-sulfonatethe copolymerizate'm 'thapresgncefiof' m i 28551ylene udemva'twemof "sorbltan monostituted' benzene. sulfonate saltofnanalkali metai shaving from 10 to -20 :carbon .-atcms in the allaygggfii g denvatwe of sorbltan mono' group and an alkyl substitutednaphthalene sul- .ionate'salt of: an-alkali'metal havingfrom llto.Poggzryglrylene derivative of sorbitan -mono- F145 "3 2 22 n atogs 5 gi f mggh d in ieme c o cairn m w c sai we 1 g --After the coagulation-has been-completed, it :agentrzis' a'ddedirto the-l emulsion prior 13113113 -isdesirabletoneutral-ize the pr-oductdn order-to,tcgpolymerization; of..-the-butadiene and :the maeliminate thesoapwhich coagulates along-with termi the copolymers, and to eliminatethe hydrochloric 3 1 119 meth d 013.313.1 1 11 i hi T 'idtti 'aciIdhwhicg adhlgreslto'the' garticles.1 t d bb I agent" is added tothetemulsiom.agtersthe copoiyiis is one 57 D a e t B C ag u a e ruermerization of the: bu adiene an tsaid materia. like particles into asolution of 1% to10% sodium 4.5:In aimethod 'for making'a fine-crumbrubhydroxide or potassium hydroxideunder' violent her-likecopolymerizate rf mi an aquegusgemulagitation, the volume ofthehydroxide solution sion'ofbutadieneand a;materialcopolymerizable beingapproximately equal to that ofthe rubbertherewith of theclass-consisting ofstyreneea-nd likehp'artiglgs. I k t 1 th I diacrylonitrile-wgkilereijn vi"tlga-emulsion .lsi formidwbti T e m er-i ema eria is" en ree from mixing witi ew u a iene -and e :ma eria soap andexcess-alkali This is preferably done water and soap in an amount:necessary: to-iorm by treatment in kneaders which are steam heated L- sD which fi p Coagulatopen-top vessels equipped with-revolvingarms. 'ingthecopolymerizatedn:the, presence-0131mm .The arms are ,mounted inoppositely. rotating 1.0 to 1.5% byweightof the emulsion oiamalkylgroups The top Ofafihe kneader iscovered with -substituted naphthaienessulfonatea -salt loft-an afine mesh which will-not permit rubber-topass fikggggffiigzgs from :150 3 ca bon-atoms through, and aCOIlHGCtIOHlS provided inthebot- ,nmamethodiof 612mm 4 whereinuthe Samis tom into which water is forced through the I H H C0agulate until thelatter hasbeen washed comsodium salt 'alkyLnaphthalene"Sulfomc acid.pletely free of soap-and excess alkali. Water-1s v In a methodkfonmakinga finemmmb mm then drained ofi and thecopolymen-dr'iedlmthe .-berlikecopolyinerizate ofrom -=an aqueous .emul kneadel under agltat-lonsionotbutadiene and a material-copolymerizable sameiprocess cflagulation sEmployed Ltherewithvofuthe class consisting. of. styrene=.and with thecopolymerization .of .butadiene with .acryiomtme.WhQIBiIILthggrnfllsimijS foxtmd by acrylonitrile or derivativesthereof, or of styrene. .mixing withthebutadienearid thematerial-wa- Theuse of-theaddedwettingwagent for some ten and'soap-in an. amountnecessary towiormlthe emulsion, the step which comprises coagulating thecopolymerizate in the presence of from 1.0 to 1.5% by weight of theemulsion of an alkyl substituted benzene sulfonate salt of an alkalimetal having from 10 to 20 carbon atoms in the alkyl group.

7. The method of claim 6 wherein the salt is the sodium salt of alkylbenzene sulfonic acid.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date Meis et a1 Oct. 27, 1942 Semon et a1 June 19, 1945 Vanderbiltet al. Sept. 18, 1945 Zwicker Oct. 16, 1945 Svendsen July 27, 1948Rumbold Apr. 12, 1949 Davison et a1. Dec. 25, 1951

1. IN A METHOD FOR MAKING A FINE-CRUMB, RUBBER-LIKE COPOLYMERIZATE FROMAN AQUEOUS EMULSION OF BUTADIENE AND A MATERIAL COPOLYMERIZABLETHEREWITH OF THE CLASS CONSISTING OF STYRENE AND ACRYLONITRILE WHEREINTHE EMULSION IS FORMED BY MIXING WITH THE BUTADIENE AND THE MATERIALWATER AND SOAP IN AN AMOUNT NECESSARY TO FORM THE EMULSION, THE STEPWHICH COMPRISES COAGULATING THE COPOLYMERIZATE IN THE PRESENCE OF FROM1.0 TO 1.5% BY WEIGHT OF THE EMULSION OF A WETTING AGENT OF THE CLASSCONSISTING OF AN ALKYL SUBSITTUTED BENZENE SULFONATE SALT OF AN ALKALIMETAL HAVING GROUP AND AN ALKYL SUBSTITUTED NAPHTHALENE SULGROUP AND ANALKYL SUBSTITUTED NAPHTHALENE SULFONATE SALT OF AN ALKALI METAL HAVINGFROM 1 TO 3 CARBON ATOMS IN THE ALKYL GROUP.